In our new world of rechargeable devices and constant connection, more battery power is never a bad thing. Seeing a battery indicator at 5% and a device begging to be recharged sends many people into a scramble looking for the nearest convenient charging solution. When there’s no outlet available or when you don’t want to leave your device tethered to a wall for the next hour, miniature USB chargers can be a lifesaver whether you’re on the road trying to summon assistance on your phone or just trying to buy some more time on your tablet at a crowded conference.

I’ve tried out a couple of portable chargers lately, the latest by RavPower, pictured above. Operation is as simple as it can get – charge the portable charger using the micro-USB port and a standard wall charger and then, when your device needs recharging, use the included USB cord to connect your device to the charger. The RavPower automatically determines the best amperage (the speed at which power is delivered) to use for your device. A higher amperage can cut down on the amount of time that it takes to get a full charge.

Regardless of the brand, these devices will be advertised with a milliampere/hour (mAh) rating which indicates the amount of electric charge the charger can hold and deliver to your devices. The packages will also often say something like “up to 1x charge” or “up to 2x charge for your phone” (emphasis mine). It’s important to remember that some phones and devices use more power than others and might not get as much operating time from one of these chargers as other devices. For example, I was able to charge the Alcatel phone you see pictured on the right from 6% to 100% in about two hours using the 3000 mAh RavPower while my Kindle Fire tablet drained the 2200 mAh PNY charger I tested earlier pretty quickly, going from about 55% to only 85%.

These chargers are a handy solution for high-use devices and small enough to fit in a pocket or laptop bag for easy access when you need them. The price depends on the model and somewhat on the mAh rating but you can get 2200 to 3000 mAh of charge for between $8 and $15 so it’s best not to overspend and just get extra chargers as you need them. You should also pay attention to the actual amperage rating (the rate at which the electric charge is delivered to your device) and whether the charger is able to adjust its amperage to the device’s needs as this is going to affect the speed of the recharge and maybe even whether its safe to use with a specific device.  Also, if you’re in the habit, as I am, of reusing USB cables interchangeably as long as the connectors fit, understand that some USB cables, like the one shown in the picture above, are charge-only and do not transfer data. I tried using that cable to connect my phone to my laptop and wondered why there was no connection being made. Sure enough, it was the cable.